The present invention relates to a closure cap to be fixed in place, preferably by screwing, plugging and rotating, on, for example, a fixed connector of a motor vehicle radiator, a compensator reservoir for cooling or heating systems, or the like.
Closure caps of this type are used, for example, in motor vehicle cooling systems, either directly as a radiator cap or as the closure of the compensator reservoir. The closure cap can either be screwed on by means of a screw thread, or it can be plugged on and turned by means of a bayonet element. In connection with motor vehicles there is a problem with respect to the closure caps, due to as a rule the pressure is high because the high temperature in the cooling system. Even if at the time of stopping the engine the temperature in the cooling system is not excessive, it is possible that after turning the engine off a temperature and therefore a pressure increase can take place because of a certain after-heating effect. If in such a case the closure cap is immediately removed, there is the acute danger of scalding for the respective user. This danger exists in particular also with screwable caps, since in the course of unscrewing the closure cap the user is not urged to slow the unscrewing process in the last phase, or better yet to interrupt it and mainly to wait until a pressure equalization with the ambient air has taken place. Although a ventilated connection between the cooling system and the exterior is opened in the course of unscrewing the closure cap, this cannot take place as rapidly as the user can possibly unscrew the closure cap. The same applies correspondingly when using a cap provided with a bayonet closure.
It is therefore an object of the present invention to provide a closure cap of the type mentioned at the outset, which cannot be removed if the cooling system is still at an excess temperature, but only after the excess temperature has been completely reduced, and which nevertheless is constructed in a space saving manner.
This object is intended to be attained by means of a closure cap having an actuating element, a temperature-dependent control element in the form of a memory spring, a control bolt, and a return spring with a collar. The memory spring is disposed off-centered and seated in an axial recess in the cap or in the actuating element. The control bolt directly causes coupling or uncoupling of the cap and the actuating element, or the memory spring is centrally disposed and a horizontal connecting leg of a U-shaped coupling element rests above the actuating element on the end of the axial control bolt facing the cap. The memory spring is acted upon by a return spring, whose other end is supported on the interior surface of the cap so that lateral vertical connecting legs project from above in the direction toward the actuating element, and at normal temperatures engage axial recesses in the actuating element for achieving a connection which is fixed against relative rotation.
A closure cap is provided which cannot be removed if a critically high temperature still prevails in the cooling system (or in the heating system). By means of this it is prevented in every case that injuries because of high temperature and the overpressure resulting therefrom in the fixed connector can occur during opening of the closure cap. The temperature-dependent control element is here housed in a space-saving manner with the coupling element.
In accordance with an exemplary embodiment it is possible to provide the temperature-dependent element between the cap and the valve or the cap and the connector, so that locking, fixed against relative rotation, of the cap with respect to the fixed connector takes place.
However, a preferred embodiment of the present invention is realized by means of an actuating element maintained rotatable with respect to the cap and that at normal temperature a coupling, fixed against relative rotation can be achieved by means of the temperature-dependent control element. In this case it has been achieved that the cap turns idly with respect to the actuating element, so that removal of the closure cap from the fixed connector is impossible, even when using force.